Materials Literature
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The first modulated structure found in decagonal Al-Ni-Fe quasicrystals [M. Saito, M. Tanaka, A. P. Tsai, A. Inoue, and T. Masumoto, Jpn. J. Appl. Phys. 31, L112 (1992)] is a superstructure in five-dimensional space with a unit cell volume identical to that in the superstructure of decagonal Al-Ni-Co. Peculiar systema…
Ion polarizabilities derived from low-frequency precision measurements of the dielectric constants of single crystals of more than 120 different oxides have recently been published but have proved difficult to interpret in terms of classical theory. The latter predicts that the polarizability of an ion should be propo…
Abstract This article discusses experiments that measure polarizabilities, permanent dipole moments, and absorption spectra of semiconductor clusters such as Si N , Ga N As M , and Ge N Te M isolated in a molecular beam. The experiments show that the transition from the typical optoelectronic properties of macroscopic…
Erbium-doped silica glasses prepared by the sol–gel process are desirable for applications in high-power lasers and integrated optical devices. However, its fluorescence could be quenched due to the high hydroxyl (OH−) content. Although this OH− content can be greatly reduced through special gas treatment [Y. Zhou, S.…
Photoluminescence spectra of porous silicon prepared with electro-chemical etching, were analyzed using a simple model based on a statistical distribution of particle size. It was found that the size of nanoparticles, obeys the logarithmic normal distribution in all the porous silicon investigated here. This model als…
Assembly of units in an alternating disrotatory fashion is a feature of the solid-state structure of an achiral, synthetic cyclic decasaccharide composed of ten α-(1→4)-linked, alternating D- and L-rhamnopyranose residues. The unit cell contains two crystallographically independent, Ci-symmetrical, cylindrical molecul…
We report in this paper optical absorption and electron paramagnetic resonance (EPR) results obtained on -doped phosphate glasses. Optical absorption allowed us to evaluate the crystal-field parameters , B and C. Electron paramagnetic resonance measurements indicate that ions are located in sites with low symmetry and…
The carrier transport of a new calamitic liquid crystal, i.e., 2-(4′-octylphenyl)6-dodecyloxynaphthalene (8-PNP-O12) was investigated by the time-of-flight technique. The fast ambipolar electronic conduction was observed in two smectic phases of 8-PNP-O12. The carrier mobilities were determined to be 1.6×10−3 cm2/V⋅s…
We report on the characterization of selectively doped GaAs/AlGaAs heterostructures, grown by an extremely clean molecular beam epitaxy system, which exhibit a Hall mobility of a two dimensional electron gas exceeding 10×106 cm2/Vs for a wide range of undoped spacer layer thickness (50–100 nm). A maximum electron mobi…
We measure the dielectric dispersion of CdSe nanocrystal colloids and show the existence of large dipole moments of 25 and 47 debye for 34 and 46 \AA{} diameter nanocrystals, respectively. The magnitude is consistent with the expected spontaneous polarization of the bulk wurtzite CdSe lattice and implies a potential d…
For Heck reactions and hydroformylations dendrimers loaded with palladium (for example 1) or rhodium are suitable catalysts. A dendrimer with 16 outer bis(diphenylphosphinomethyl)amino end groups has been synthesized in one step by phosphinomethylation of a commercially available polyamino-dendrimer and converted into…
The desorption kinetics of molecular beam deposited ultrathin films of CC${\mathrm{l}}_{4}$ and amorphous solid water (ASW) are studied. Overlayers of ASW impede CC${\mathrm{l}}_{4}$ desorption until the onset of crystallization, whereupon the CC${\mathrm{l}}_{4}$ desorbs abruptly. The abrupt desorption occurs through…
High molecular weight block copolymers can be viewed as macromolecular surfactants when blended with thermodynamically incompatible homopolymers. This Letter describes the formation of polymeric bicontinuous microemulsions in mixtures containing a model diblock copolymer and two homopolymers. Although we attribute dev…
A relative molar mass of 40 000 and diameter of 4 nm are the remarkable dimensions of the title anion, which is, together with its LaIII analogues, the most massive inorganic water-soluble cluster so far observed (see picture on the right). These polyanions with 164 metal atoms are easily synthesized in fair yield. Th…
Abstract The design and performance of a new instrument, based on improved Penning ion guns [1] for etching and coating samples for SEM and LM in a single vacuum chamber, are described. The instrument is based on an existing high resolution ion beam coating system, which is capable of producing high quality ultra-thin…
Abstract Cu2O is a semiconductor with a band gap of 2.17eV, and its crystal structure is simple cubic. Oxygen atoms form a bcc structure and each oxygen atom is tetrahedrally coordinated by copper atoms, which makes copper linearly coordinated by two oxygen atoms. The structure of cuprite is interesting because the ch…
We report on a study of mixtures of octylcyanobiphenyl (8CB) and equal amounts of two chiral agents (CE2 and CB15) as a function of chiral pitch (concentration). Bulk studies reveal a widening cholesteric temperature range with increasing chirality. The first order cholesteric-isotropic (Ch-I) transition shifts margin…
Diffuse reflectance infrared spectroscopy and static secondary ion mass spectrometry (SIMS) were employed to study the surface species formed during the adsorption and reaction of propylene on a copper-exchanged ZSM-5 catalyst. Propylene showed characteristics of chemisorption on Cu-ZSM-5 at room temperature and total…
A new effect of illumination on ionic conductivity and activation energy of migration of mobile Ag + cations in RbAg 4 I 5 superionic crystals has been detected and studied. Reversible changes in the ionic conductivity due to illumination of superionic crystals are caused by reversible changes in the structure of elec…
We propose a model describing the destruction of metals under ultrashort intense laser pulses when heated electrons affect the lattice through the direct electron-phonon interaction. The metal consists of hot electrons and a cool lattice. The lattice deformation is estimated immediately after the laser pulse up to the…